Field of Invention
The present invention relates to a new glass lined reaction tank for chemical and pharmaceutical industries and a manufacturing method thereof, and belongs to the field of pressure vessel apparatuses for chemical and pharmaceutical industries.
Description of Related Arts
Glass lined reaction tanks belong to Class II pressure vessel reaction apparatuses. A tank body of each glass lined reaction tank consists of an inner cylinder body (an inner wall of which is coated and sintered with a glass lining layer) and an outer jacket. At present, electric furnaces for sintering the glass lined reaction tanks at home and abroad are all external heating type electric furnaces, and iron blanks thereof are all manufactured by adopting secondary processing molding. Firstly, a glass lining layer of an inner wall of the inner cylinder body with an upper connecting ring and a lower connecting ring (transitional structure members of the outer jacket) is sintered, then the outer jacket is assembled and welded, and a single-sided circumferential butt welding seam added with a lining plate is formed at the position of the upper connecting ring thereof. Chinese standards Technical Conditions for Glass Lined Equipment (HG2432-2001) issued on Jan. 24, 2002 regulate that nondestructive testing can be exempted to be performed to the circumferential welding seam at this position, which is obviously not in compliance with the manufacturing specifications of pressure vessels, resulting that the Chinese “technical standards” for manufacturing the glass lined reaction tanks are not recognized by other countries in the world. For this reason, Chinese standards Technical Conditions for Glass Lined Equipment (GB25025-2010) issued on Sep. 2, 2010 regulate that surface nondestructive testing shall be performed to the circumferential welding seam at this position, which however is not in compliance with the manufacturing specifications of variable-pressure vessels.
Since the iron blank of the tank body is manufactured by adopting secondary processing molding, consequently three major serious product quality problems are caused and are difficult to solve. For the inner cylinder body provided with the upper connecting ring and the lower connecting ring and formed by single-layer steel plates, after 6-8 times of high-temperature roasting at approximately 900° C., a basal body is integrally deformed and presents distorted skirt type deformation. When the upper connecting ring is assembled and welded with the cylinder body of the jacket, firstly shaping is forcibly performed, then electric welding is performed, consequently high-temperature shock and welding seam stress cause potential hazards such as micro-cracks to the glass lining layers, and as a result, the overall quality of the glass lining layers is seriously influenced.
For an external heating type electric furnace, heat released by electric heating power thereof firstly radiates the outer wall of the steel plates of the inner cylinder body and then is transferred to the glass lining layers on the inner wall. Accordingly, it can be seen that what is measured and controlled thereby is the temperature of the furnace body. In addition, the thickness of a steel plate of a high-neck big flange on the inner cylinder body is 2.5 times of the thickness of a straight cylinder body, the heat capacity needed thereby is great, a group of upper and lower connecting ring structure components and a supporting frame or a hanger sintered by using a product exist on the outer side of the inner cylinder body form flame barriers to the external heating type electric furnace during heating, heating temperature of the glass lining layers on the inner walls of the above parts is obviously lower than that of other parts, consequently the temperature controlled by the controlled sintering “core technique” executed by the external heating type electric furnace is not the actual heating temperature of the glass lining layers, the heating is not even, the temperature difference is great and the remarkable improvement of the overall quality of the product is directly influenced.
Since the glass lined reaction tank is repetitively sintered at high temperature in the external heating type electric furnace, the deformation of the basal body causes the big flange of the apparatus to be integrally deformed, the sealing performance of the tank mouth of the reaction tank is directly influenced, consequently reaction medium gas in the tank is caused to leak, and problems of environmental protection and safety production are involved. As a result, clips have to be forcibly tightened during use and the glass lining layer on the surface of the big flange is caused to be cracked. According to the new national standards Technical Conditions for Glass Lined Equipment (GB25025-2010), when difference between maximum diameter and minimum diameter of the flange of the apparatus should be smaller than or equal to 6 mm when DN is smaller than or equal to 1000 mm, and should be smaller than or equal to 10 mm when DN is greater than 1000 mm; flatness tolerance should be smaller than or equal to 2 mm when DN is smaller than or equal to 1000 mm and should be smaller than or equal to 2.5 mm when DN is greater than 1000 mm; and width of a pressed face of the flange of the apparatus should be greater than or equal to 15 mm.
When the damaged glass lining layer of the reaction tank is repaired, at the welding position between upper and lower connecting ring transition pieces and the outer jacket, the outer jacket needs to be cut off by using oxy-acetylene flames, then the single-sided circumferential welding joint which is not flat and straight, is curved and is added with the lining plate are welded again with the lower connecting ring to form the tank body after the glass lining layer is repetitively sintered and inspected as qualified, and this is not in compliance with the repair specifications of the pressure vessels. According to reports, explosion accidents were ever caused for this reason.
The glass lined reaction tanks belong to high-value consumables and are damaged generally after 1-2 years of use. It should be pointed out that the area of the damaged glass lining layers of a considerable quantity of reaction tanks only accounts for 0.05% of the total area and some only have several small point area damages. In China, a great number of reaction tanks which are worth several hundred millions of Chinese Yuan and consume several ten thousands of tons of steel materials are discarded every year for a reason that the glass lining layers are damaged and cannot be repaired for reuse, the steel materials are greatly wasted and the capital losses are serious.
Therefore, the present invention deeply develops one-step molding “technical standards” of the iron blank of the tank body of the glass lined reaction tank and innovatively manufactures a high-grade new glass lined reaction tank which has Chinese pioneer creative independent intellectual property and overall quality which is superior to the international advanced level, so as to drive a great revolution of the glass lining industry in the modern world.
Patent CN201110287709.0 discloses a glass lined reaction tank which is sintered by adopting an internal heating type electric furnace. However, this glass lined reaction tank still cannot thoroughly eliminate various potential hazards and defects in the integral glass lining layers to the utmost extent, the nominal pressure of the tank mouth big flange and the sealing performance of the tank mouth still cannot be perfectly improved, and it is difficult to manufacture a glass lined reaction tank which comprehensively satisfies requirements on Class III pressure vessels.